Zinc salts of p2s5-olefin-chloral reaction products as extreme pressure agents



United States Patent r 3,093,584 ZINC SALTS OF P S -0LEFlW-CHL9RALREACTION PRODUCTS AS EXTREME PRESSURE AGENTS Richard L. Ferm, ElCerrito, Califi, assignor to California Research Corporation, SanFrancisco, Cnlif.,a curporation of Delaware No Drawing. Filed Aug. 8,1960, Ser. No. 47,945 7 Claims. (Cl. 25232.7)

This invention relates to lubricating oil compositions containingoil-soluble agents which are effective in imparting extreme pressurecharacteristics to the lubricating oil compositions.

It is well known that the normal lubricating oil compositions used forthe lubrication of various parts of internal combustion engines,automobile chassis, and machinery in general are likely to fail whenunusually heavy pressures are applied thereto.

in the automotive field, in order that automobiles may be built withless height, it has been necessary to provide smaller gears throughoutthe automobile assembly. Although these gears are smaller, the powerrequirements from the engines themselves have continued to increase. Asa consequence, the smaller bearing and gears carry larger loads per unitarea than was heretofore necessary with the larger bearings. Pressuresin the order of hundreds of thousands of pounds per square inch areexerted in the hypoid gear assemblies so commonly used in automotivevehicles. If such pressures result in the squeezing out, as it were, ofall of the oil between the contacting metal surfaces, thesemetalsurfaces will contact each other directly, resulting in the formation.of extremely high temperatures due to friction, terminating with seizureor excesive wear and early failure of the metal wearing parts.

It is known from the prior art, for example, that zinc alkyldithiophcsphates derived from P 8 and alcohols are useful in lubricantcompositions as extreme pressure agents. However, lubricants havingextreme pressure characteristics mount to be characterized only as such,

' but in addition, such lubricants should have high lubricating filmstrength, impart low rates of Wear and low coefficients of friction.However, the new extreme pressure additives described herein areconsiderably superior to the prior art additives in these respects.

It is a primary object of this invention to set forth lubricating oilcompositions having extreme pressure characteristics that do not sufferloss or deterioration of high film strength, low rates of wear, or lowcoefiicients of friction in long continued use under severe conditions.

Therefore, in accordance with this invention, it has been discoveredthat lubricating oil compositions having high extreme pressurecharacteristics are obtained by incorporating therein the zinc salt ofthe product obtained by reacting (a) a phosphorus sulfide with an olefin(b) reactingthe product obtained from (a) with chloral, (c) reacting theproduct'obt'ained from (b) with Zinc oxide or hydroxide).

The lubricating oil compositions described herein not only have highextreme pressure characteristics, but they also have excellent oxidationstability;

The phosphorus sulfide used herein as a reactant is preferablyphosphorus pentasulfide (i.e., P 8

The olefins are polymers of propylene and butylene,

c CC

which polymers have molecular weights in the range of about l75 to about500. That is, the olefins used herein in reaction with the phosphorussulfides are polypropylenes or polybutylenes having molecular weights inthe range of 175 to 500. V

The reaction between phosphorus sulfides and polyolefins is welldescribed in numerous patents, which set forth various reactionconditions.

However, for the new products described herein, it is preferred that thepolyolefins and the phosphorus pentasulfide are used in molar ratios ofabout 2 mols of polyolefins per mol of phosphorus sulfide. For thepurpose of simplicity, the product obtained by reacting phosphoruspentasulfide and the polyolefin will be termed herein aphosphosulfurized polyolefin.

The phosphosulfurized polyolefin is reacted with chloral in equivalentproportions at temperatures ranging from 25 C. to 150 C. The resultingacidic product is neutralized with a basic zinc compond, such as zincoxide or zinc hydroxide, to form the zinc salt. It is this zinc saltwhich is the extreme pressure agent of this invention. 1

The phosphosulfurized polyolefins are prepared by reacting thepolyolefins and the phosphorus pentasulfide at temperatures ranging from120 C. to 290 C., preferably from 150 C. to 240 C.

The-reaction of the phosphosulfurized polyolefin with chloral can bestbe done at 0 C. to 150 C., more prefer: abiy, 100 C. to 140 C.

The phosphosulfurized polyolefin-chloral acidic product can beneutralized with zinc oxide (or hydroxide) at temperatures of 50 C. to75 C. to form the zinc salt thereof, which zinc salt is the extremepressure agent of this invention.

The zinc salt described hereinabove is used in lubricating oilcompositions in amount sufiicient to impart extreme pressurecharacteristics thereto, that is, in amounts from about 0.1%, by weight,to about 25%, by weight. The zinc salt is preferably used in amounts of1.0% to 15% by weight.

Thus, the lubricating oil compositions of this invention haveincorporated therein a zinc salt of aphosphosulfurized-polyolefin-chloral reaction product which zinc salt isobtained by reacting zinc oxide (or hydroxide) at 50 to C. with aphosphosulfurized polyolefin-chlora1 product prepared by reacting aphosphosulfurized-polyolefin with chloral in equivalent proportions attemperatures from 0 C. to C.

Lubricating oils which can be used as base oils include a wide varietyof lubricating oils, such as naphthenic base, paramn base, and mixedbase lubricating oils, other hydrocarbon lubricants, e.g., lubricatingoils derived from coal products, and synthetic oils, e.g., 'alkylenepolymers (such as polymers'of propylene, butylene, etc.,"and themixtures thereof), alkylene oxide-type polymers (e.g., propylene oxidepolymers) and derivatives, includingalkyleue oxide polymers prepared bypolymerizing the alkylene oxide in the presence of water or alcohols,e.g., ethyl alcohol, dicarboxylic acid esters (such as those which areprepared by esterifying such dicarboxylic acids as adipic acid, azelaicacid, suberic acid, sebacic acid, alkanol succinic acid, fumaric acid,maleic acid, etc., with alcohols such as butyl alcohol, hexyl alcohol,Z-ethyl hexyl alcohol, dodecyi alcohol, etc.) liquid esters of acids ofphosphorus, akyI'benzenes (e.g., monoalkyl benzene such as dodecylbenzene, tetradecyl benzene, etc.), and dialkyl benzenes (e.g., n-nonyl2-ethyl hexyl benzene); polyphenyls (e.g., biphenyls and terphenyls),alkyl biphenyl ethers, polymers of silicon (e.g., tetraethyl silicate,tetraisopropyl silicates, tetra(4-methyl-2-tetraethyl) silicate, hexyl(4-methyl-2-pentoxy)disiloxane, poly(methyl) siloxane,poly(methylphenyl) siloxane, etc.). Synthetic oils of the alkyleneoxide-type polymers which may be used include those exemplified by thealkylene oxide polymers.

The above base oils may be used individually or in combinations thereof,whenever miscible or wherever made so by the use of mutual solvents.

The examples set forth hereinbelow describe the preparation of theextreme pressure agents of this invention.

EXAMPLE 1 Preparation of Phosphosulfurized Polybutene and found tocontain:

Phosphorus percent by weight 2.67 Sulfur do 7.33 Atomic ratio, S/P 2.57

EXAMPLE 2 Preparation of ihe Zinc Salt of Phosphosulfurized Polybutene Amixture of 1,000 grams (0.875 g.-atoms phosphorus) of the filteredreaction product of Example 1 hereinabove, and 126.3 grams (0.857 mol)of chloral was blended with agitation and heated at the followingtemperatures during the noted periods of time:

Time, hrs: Temp. C. 0.0 40 0.25 100 2.0 137 2.25 145 3.0 55

After the three-hour period, the mixture was cooled to room temperature,after which 36.5 grams (0.449 mol) of zinc oxide was added. On thisaddition, the temperature rose to 76 C. The mixture was then agitatedfor a period of about 2 hours at 75 C. to complete the reaction.

The contents of the reaction flask, after standing overnight at roomtemperature, were heated to a temperature of 70 C. liquid temperature at7 mm. Hg absolute pressure. The fluid remaining in the reaction vesselwas a dark, oil-soluble liquid which was found on analysis to contain:

Phosphorus, wt. percent 2.04, 2.02

Sulfur, wt. percent 6.06, 6.12

Zinc, wt. percent 1.99, 2.01

Chlorine, wt. percent 7.4, 7.1

Atomic ratios: PLQO, S2 90, ZHOAGB, C1342- Acid number (Mg KOH/g.) 24.2

EXAMPLE 3 Preparation of Ph'osphosulfurized Polypropylene A mixture of729.2 grams (4.00 mols) of propylene tetramer (mol wt. 182.3) and 446.5grams (2.01 mols) of phosphorus pentasulfide was heated from 75 C. to

138 C. during a 2-hour period, followed by heating to a temperature of150 C. during an additional 3.5 hours. The contents of the reactionvessel were filtered through Celite filter aid, and the clear filtrate,approximately 1,165 grams, was analyzed and found to contain:

Phosphorus, wt. percent 9.52 Sulfur, wt. percent 25.8, 26.2 Atomicratio, S/P 2.64 Density, 20/4 1.0814 Refractive index, n 1.5778

The resulting material was soluble in a solvent refined Mid-Continentbase SAE 30 oil at a temperature of about 180 F., but practicallyinsoluble at room temperature.

Example 4 Reaction of Phosphosulfurized Polypropylene With Chloral andZinc Oxide A mixture of 239.5 grams (0.735 g.-atoms phosphorus) of thephosphosulfurized polypropylene from Example 3 hereinabove and 123.7grams (0.840 mol.) of freshly distilled chloral was blended at 70 C. Theresulting exothermic reaction raised the temperature with water bathcooling to C. The mixture was then heated at temperatures ranging fromC. to C. for a period of about 3 hours during which time the color ofthe mixture changed from a light yellow to a dark red. The reactionproduct was cooled to 50 C., at which temperature 36 grams (0.4420) ofzinc oxide was added. It was necessary to apply cooling to keep thetemperature at about 65 C. The temperature was kept at that point forabout 1.5 hours, after which the product was heated at 75 C. liquidtemperatures and absolute pressure of 25 mm. Hg to remove water andunreacted chloral or chloral hydrate. The reaction mixture was thenfiltered through Celite filter aid, yielding a clear, dark viscousliquid, which, on analysis, was found to contain:

A mi ratios! rom 2.02 0.495 2.87-

In an amount of 10%, by weight, this zinc salt was insoluble in asolvent refined Mid-Continent SAE 30 oil, and in a California parafiinicbase oil having a viscosity of 895 SSU at 100 F. However, in an amountof 10%, by Weight, this zinc reaction product was soluble in DowPolyglycol 144, a mixed poly (ethylene, propylene) glycol 2-ethyl hexylmethyl diether having a molecular weight of about 400. This oil is soldby Dow Chemical Company.

Table I hereinbelow presents extreme pressure data obtained by theFederal Test Method Standard No. 791, using a Shell 4-Ball Tester, withthe exception that the tests herein were run at 500 r.p.m. instead ofthe specified 1,000 r.p.m.

The additives were present in the lubricating oil composition in anamount sufficient to provide 0.10 gram atom phosphorus per liter oflubricating oil composition.

The base oil was a California paraflin base oil having a viscosity of 95SSU at 210 F. (viscosity index=85).

Additive A was a zinc di(alkylphenyl) dithiophosphate wherein the alkylradicals were derived from propylene polymers having an average of about12 carbon atoms.

Additive B was a zinc salt of a mixed dialkyl dithiophosphoric acidwherein one of the alkyl radicals contained 4 carbon atoms and the otheralkyl radical contained 6 carbon atoms.

Additive C was a zinc mixed dialkyl dithiophosphate wherein one of thealkyl radicals contained 4 carbon atoms and the other alkyl radicalcontained 5 carbon atoms.

Additive D was the zinc salt obtained in Example 2 hereinabove.

TABLE I Load at failure, Test No Additive pounds 1 None 85 A 210 B 335 C325 D 410 Table II hereinb'elow presents data showing fiurther theeffectiveness of the zinc salts herein as wear reducing agents asdetermined by the Falex test, which is described in Journal of theInstitute of Petroleum, volume 32, April 1946. The test assemblyconsisted of a steel rod inserted between two steel Vashaped bearingblocks. The assembly bearing blocks and rod were immersed in thelubricating oil being tested. The rod was rotated and, as the rodrotated, progressively increasing pressures were applied upon the rod bythe V-shaped bearing block' until seizure occurred. The numericalfigures of table II are the recorded Falex values at which seizureoccurred; that is, the loads under which the particular lubricating oilcompositions failed.

The base oil was Squibbs White Oil, and the additive level was such asto provide 0.01 gram. atom of phosphorus per liter of oil composition.

The lubricating oil compositions described herein are not only highlyeffective'under conditions of high pressure, that is, Where extremepressure characteristics are desired, but these lubricating oilcompositions are also highly resistant to oxidation. The anti-oxidationproperties of these lubricating oil compositions were evaluated in testswherein the oxidation inhibition periodwas determined. The data arepresented hereinbelow in table 111.

By this oxidation test, the lubricating oil composition was placed in alarge glass tube equipped with a high speed glass stirrer, incorporatingtherein as oxidation catalysts several metal naphthenates in amountssuificient to provide the metal concentration as follows:

The oil temperature was maintained at 340 F., at a pure oxygen pressureof about 1 atmosphere. The inhibition period was the time in hoursrequired for 100 grams of oil to absorb 1200 cc. of oxygen. Theinhibition period for the base oil is typically to 30 minutes in thistest.

Base oil A, which was a blend of Mid-Continent paraffin base oils, had aviscosity of 127.3 SSU at 100 F., and 41.3 SSU at 210 F. The viscosityindex was 89.4.

Base oil B was the Dow-Polyglycol 144 described hereinabove.

Additive A was a commercial lubricating oil additive concentrate whenused in the amount noted, provided in the finished oil composition 0.4%,by weight, of a commercial oxidation inhibitor, about 0 .5%, by Weight,of a corrosion inhibitor, and 4.67 rum/kg. (millirnols per kilogram oifinished oil, based on the zinc) of a zinc mixed dialkyl dithiophosphatewherein one alkyl radical alkyl radical con- TABLE III Test No l0 11 12Temperature, "F 340 340 340 Lube Oil Composition, weight percentase oilA 81.2 78. 2 Base Oil B. 83.2 Additive A. 6. 8 6. 8 6. 8

Additive B 12.0

Additive C 15.0 Additive D 10. 0 Inhibition period, hours 4. 5 7. 2 1.9

I claim:

1. A lubricating oil composition comprising a major proportion of an oilof lubricating viscosity selected from the group consisting of mineraloil and synthetic oil and mixtures thereof, and from 0.1% to 25%, byweight, of a zinc salt of a phosphosulfurized polyolefin-chloralreaction product, which product is obtained by reacting in equivalentmolar amounts a phosphosulfurized polyolefin with chloral attemperatures in the range of 0 C. to 150 C., where saidphosphosulfurized polyolefin is a product obtained by reactingphosphorus pentasulfide with a polyolefin at temperatures in the rangeof about 120 C. to about 290 C. wherein the phosphoruspentasulfidepolyolefin niol ratio is 1:2, and said polyolefin isselected from the group consisting of polypropylene and polybutylenehaving molecular weights fromabout 175 to about 500. t

2. A lubricating oil composition comprising a major proportion of an oilof lubricating viscosity selected from the group consisting of mineraloil and synthetic oil and mixtures thereof, and from 0.1% to 25 byweight, of a zinc salt of a phosphosulfurized polyolefin-chloralreaction product, which product is obtained by reacting in equivalentmolar amounts a phosphosulfurized polyolefin with chloral attemperatures in the range of C. to 140 C., where said phosphosulfurizedpolyolefin is a product obtained by reacting phosphorus pentasulfidewith a poly-olefin at temperatures in the range of about C. to about 290C. wherein the phosphorus pentasulfidepolyolefin mol ratio is 1:2, andsaid polyolefin is selected from the group consisting of polypropyleneand polybutylene having molecular Weights from about 175 to about 500.

3. A lubricating oil composition having extreme pressure characteristicscomprising a major proportion of an oil of lubricating viscosityselected from the group consisting of mineral oil and synthetic oil andmixtures thereof, and from about 1% to about 15%, by weight, of a zincsalt of a phosphosulfurized polyolefin-chloral reaction product, whereinthe reaction product is obtained by reacting, in equivalent molaramounts, chloral with a phosphosulfurized polyolefin at temperaturesfrom about 100 C. to about (1., wherein said phosphosulfurizedpolyolefin is prepared by reacting 2 mob of a polyolefin selected fromthe group consisting of polypropylene and polybutylene having amolecular Weight from about to about 500 with 1 mol of phosphoruspentasulfide at temperatures from about 120 C. to about 280 C.

4. A lubricating oil composition consisting essentially of an oil oflubricating viscosity selected from the group consisting of mineral oilsand synthetic oils and mixtures thereof and from about 0.1% to about25%, by weight, of a zinc salt of a phosphosulfurized polyolefin-chloralproduct, which product is obtained by reacting, in equivalent molaramounts, 9. phosphosulfurized polyolefin with chloral at temperatures of100 C. to 140 C., wherein said phosphosulfurized polyolefin is a productobtained by reacting P S with a polyolefin, wherein the phosphoruspentasulfidepolyolefin mol ratio is 1:2 and wherein said polyolefin in apolybutene having molecular weight in the range of about 175 to about500 and wherein said P S -polyolefin reaction is at temperatures in therange of 120 C. to about 290 C.

5. A lubricating oil composition consisting essentially of a petroleumbase oil and from about 0.1% to about 25 by Weight, of a zinc salt of aphosphosulfurized polyolefin-choral product, which product is obtainedby reacting, in equivalent molar amounts, a phosphosulfurized polyolefinwith choral at temperatures of 100 C. to 140 C., wherein saidphosphosulfurized polyolefin is a product obtained by reacting P S witha polyolefin, wherein the phosphorus pentasulfide-polyolefin mol ratiois 1:2 and wherein said polyolefin is a polybutene having molecularweight in the range of about 175 to about 500 and wherein said P S-polyolefin reaction is at temperatures in the range of 120 C. to about290 C.

6. A lubricating oil composition consisting essentially of a petroleumbase oil and from about 0.1% to about 25%, by weight, of a zinc salt ofa phosphosulfurized polyolefin-choral product, which product is obtainedby reacting, in eqivalent molar amounts, a phosphosulfurized polyolefinwith choral at temperatures of 100 C. to

140 C., whereinsaid phosphosulfurized polyolefin is obtained by reacting1 mol of phosphorus pentasulfide with 2 mols of a polybutene having amolecular weight of about 175 to about 500 at temperatures in the rangeof 120 C. to about 280 C.

7. A lubricating oil composition consisting essentially of a petroleumbase oil and from about 0.1% to about by weight of a zinc salt of aphosphosulfurized polyolefin-chloral product, which product is obtainedby reacting (A) phosphorus pentasulfide with a polybutene having amolecular Weight of about 175 to about 500 at temperatures in the rangeof C. to about 280 C., wherein the phosphorus pentasulfide polybutenemol ratio is 1:2, (B) reacting a product from (A) with chloral inequivalent molar amounts at temperatures of 100 C. to about C., (C)reacting the product of (B) with zinc oxide to form the zinc saltthereof.

References Cited in the file of this patent UNITED STATES PATENTS2,444,948 Musselman et a1 July 13, 1948 2,703,784 Fields Mar. 8, 19552,727,030 Beretvas Dec. 13, 1955 2,827,433 Fischl et a1 Mar. 18, 19582,833,714 Richardson et a1 May 6, 1958 2,939,841 Buckrnan June 7, 1960

1. A LUBRICATING OIL COMPOSITION COMPRISING A MAJOR PROPORTION OF AN OILOF LUBRICATING VISCOSITY SELECTED FROM THE GROUP CONSISTING OF MINERALOIL AND SYNTHETIC OIL AND MIXTURES THEREOF, AND FROM 0.1% TO 25%, BYWEIGHT, OF A ZINC SALT OF A PHOSPHOSULFURIZED POLYOLEFIN-CHLORALREACTION PRODUCT, WHICH PRODUCT IS OBTAINED BY REACTING IN EQUIVALENTMOLAR AMOUNTS A PHOSPHOSULFURIZED POLYOLEFIN WITH CHLORAL ATTEMPERATURES IN THE RANGE OF 0*C. TO 150*C., WHERE SAIDPHOSPHOSULFURIZED POLYOLEFIN IS A PRODUCT OBTAINED BY REACTINGPHOSPHORUS PENTASULFIDE WITH A POLYOLEFIN AT TEMPERATURES IN THE RANGEOF ABOUT 120*C. TO ABOUT 290*C. WHEREIN THE PHOSPHORUSPENTASULFIDEPOLYOLEFIN MOL RATIO IS 1:2, AND SAID POLYOLEFIN IS SELECTEDFROM THE GROUP CONSISTING OF POLYPROPYLENE AND POLYBUTYLENE HAVINGMOLECULAR WEIGHTS FROM ABOUT 175 TO ABOUT 500.